高考语法——情态动词.ppt

情态动词情态动词的特征情态动词的变化形式
（1）没有人称和数的变化。
Ican/wecan/hecan/itcan
Johnny,youmustn’tplaywiththeknife,youmayhurtyourself.
Heoughttoknowheraddress.
Aleftluggageofficeisaplacewherebagscanbeleftforashorttime.
（2）大部分情态动词有过去式：
could，might，neededdared，
shall-should，would–IsJohncomingbytrain？
–Heshould,buthemaynot.Helikesdrivinghiscar.
-AreyoucomingtoJeff'sparty?
-I'mnotsure.Imightgototheconcertinstead.
（3）少部分情态动词没过去式或者说过去式与原形相同，usedto只有过去式形式。
must，oughtto
Iusedtogothere.
Youmustbetiredafteryourlongjourney.（4）大多数情态动词后面还可跟动词的进行时、完成时和被动式形式：
can/may/must/should/would/might+
bedoing/havedone/bedone
Hemusthaveearnedalargesumofmoney.
Youmustn’talwaysbetalkingsomuch.
否定式和疑问式
情态动词的否定式和疑问式和助动词相同。否定式是在情态动词后加not；疑问式是将情态动词提前到主语的前面。cannot=can't,maynot=mayn't
mustnot=mustn't,neednot=needn't
couldnot=couldn't,darenot=daren't
mightnot=mightn't,willnot=won't
shouldnot=shouldn't
wouldnot=wouldn't,shallnot=shan't
oughtnotto=oughtn'tto
usednotto=usen'tto
-Willyoustayforlunch?
-Sorry,Ican’t.Mybrotheriscomingtoseeme.
MayIaskyouaquestion?
Iwasreallyanxiousaboutyou.Youshouldn’thavelefthomewithoutaword.
注意：haveto的疑问和否定借助于do来构成
Doyouhavetogoouttoday?
Hedoesn’thavetogo.
情态动词的基本用法
1、can和could
（1）表能力
①意为“能够会”，表示体力或脑力方面的能力Someofuscanusethecomputernow,butwecouldn'ttenyearsago.
Canyourideabike?
WhatcanIdoforyou?
Icouldrunfasterthen.
②当can和could表示能力时，有时可以用beableto替换，could表过去，can表现在，有时也可表将来，但不能与will,shall等助动词连用；beableto可以用于将来、完成等时态。
Shehasn'tbeenabletocometoschoolforthreedays.Shehasn'tbeenabletocometoschoolforthreedays.
Withhishelp,weshallbeabletobuildthehouse.
③要强调过去确实使用了某种能力时，要用was（were）ableto，而不用could。wasableto表示“设法干成某事”，即succeedindoingsth.或managedtodosth.而could只表示“具备某种能力”。
Heissuchagoodswimmerthathewasabletosavethetwoboysfromdrowning.Thefirespreadthroughthehotelbuteveryonewasabletogetout.
（2）表可能性
Ithoughtthestorycouldnotbetrue.
Anybodycanmakemistakes.
（3）表许可（常用于口语中）
Can/CouldIgonow?
HesaidIcouldusethecomputer.
-CouldIborrowyourdictionary?
-Yes,ofcourseyoucan.
Fathersaidwecouldgototheconcert.（4）表惊异怀疑、不相信等态度
①主要用于